Soybean is outstanding food stuff among the beans which have nutritionally valuable oils and fats and proteins. In particular, the soybean proteins have an amino acid score of 100 representing the nutritional value equivalent to that of animal proteins, and soybeans are hence referred to as the meat of field.
Thus, in aiming to the advanced use of soybean, the nutritional value and physical functions of particularly soybean proteins have drawn attention, and soybean protein concentrates, wherein defatted soybean mainly used as a raw material is washed with acid or alcohol and the whey component is removed therefrom (Patent Literatures 1 and 2) and soybean protein isolates, wherein defatted soybean is water extracted to extract proteins followed by removing the fibers and the obtained extract is adjusted to acidity of pH 4 to 5 to precipitate the proteins from which the whey component is removed, have been produced.
In Japan, among the world, particularly processed soybean food products have been traditionally produced and consumed. Examples of the processed soybean food product include soy flour, kinako (roasted soybean flour), soymilk, okara (soybean residue), tofu, natto (fermented soybeans), soybean paste and soy sauce. Tofu is further processed to aburaage (deep-fried thin-sliced tofu), ganmodoki (fried tofu fritter) or koyadofu (freeze-dried tofu). Many of these processed soybean food products have the flavor distinctive of soybean. The reason why the processed soybean food products have been consumed by many people for a long time is probably because the distinctive soybean flavor matches the way people eat these products.
Incidentally, in the diet of people, grain consumption tends to decrease and meat consumption tends to increase. This tendency is thought to have been accelerating by the conversion to the wheat culture brought by the westernized diet, further increased number of processed food products and meat-oriented dishes. To expand the purpose of use of processed soybean food products based on the idea of correcting the imbalanced increased consumption of animal food products in such a diet and improving the nutritional balance is conceived to direct the people's health of today in a better direction.
However, in some cases the flavor of soybean may not be preferable depending on the purpose of use. Also, the sensations of sitting heavy on the stomach or bloating may be experienced depending on processing methods, particularly when soybean is formed or consumed like or combined with a dairy product, the flavors are incompatible, sometimes making it difficult to produce fabricated food products.